pringsheim's researches on chlorophyll. 77 



I. Structure and Composition of Chlorophyll-corpuscles. 



In micro-chemical investigations of chlorophyll-corpuscles 

 hitherto made a solvent has been generally used for sepa- 

 rating the colouring matter from the ground-substance of 

 the corpuscle, a method possessing the disadvantage that 

 other substances besides the colouring matter are extracted 

 in the solution from the corpuscle, and these have not been 

 sufficiently distinguished and separated from the colouriiig 

 matter. In the investigations reco^'ded in the following 

 pages, a new method, against which such objection cannot 

 he raised, has been employed. It consists in warming 

 green tissues in water or subjecting them to the action of 

 steam or treating them with dilute acids. Different effects 

 are produced according as one or other, or a combination of 

 these agencies, is made use of; but they coincide in this 

 general effect, that they cause the colouring matter, along 

 with certain fluid or seniifluid substances accompanying it, to 

 exude from the chlorophyll-corpuscles in the form of larger 

 or smaller drops, while these coat the periphery of the deco- 

 lorised skeleton or ground-substance which itself retains the 

 original form of the corpuscle. 



If a portion of green tissue be warmed for fifteen minutes 

 to an hour in water of a temperature of 50° to 80° C, or 

 if it be suspended during fifteen minutes to several hours in 

 a flask, so as to be in contact with the steam of boiling 

 water (the degree of temperature and the time required for 

 the action varies with the tissue taken ; in most cases boiling: 

 the tissue for five minutes is the quickest and most con- 

 venient procedure), viscid drops of varying size become 

 visible at the circumference of the chlorophyll corpuscles. 

 They may be watched exuding from the substance of the 

 corpuscle, in number depending upon the duration of the 

 operation. Always coloured, they are usually chlorophyll- 

 green, but this may be brighter or darker, and the tint in 

 some cases is yellow or blue-green, occasionally olive-green, 

 more seldom reddish-brown (figs. 1 and 3). They are com- 

 pletely soluble in alcohol and ether, and consist of the 

 colouring matter with an oily basis, which is the vehicle 

 holding it and the substances accompanying it in solution. 



In proportion as the exudation proceeds, the ground- 

 substance is decolorised and the colouring matter may be 

 completely removed from it. The structure of the ground- 

 substance then becomes visible, and it appears uiider a 

 high magnifying power as a skeleton, having the shape of 

 the original chlorophyll-corpuscles, composed of a soft sub- 



